Active Shade Structure

The purpose of this project was to create a moving shade structure for plant seedlings that mimics the movement of the sun throughout the day. This structure is used to help ease the transition between plant seedlings grown indoors before being transplanted into gardens. The process of "hardening off" seedlings refers to periods of increasing outdoor exposure for young plants to get them used to sunlight, fluctuating air temperatures, and wind. These conditions are lacking indoors where we tend to create perfect and sterile environments in order to maximize seed germination. One of the main issues with this process is the amount of micromanaging it takes where a gardener must bring plants inside and outside every day, while keeping track of the amount of time outside so they may steadily increase it. A moving shade structure seeks to alleviate some of these issues by blocking direct sunlight that may cause "sun scald" due to over exposure on seedlings and allowing gardeners to leave plants outside longer, earlier. Direct sunlight may also lead to soils drying out and eroding away with the wind, forcing the gardener to be more diligent and use more water. Also, by designing the structure with an opening under the shade arm, it allows for wind to flow freely which is important for a seedling to strengthen it's stem and avoid diseases with adequate air flow. This is a base project and can be improved upon, examples could include: overall size, material strength, stronger motor, placement of photo resistors, adjustable shade cloth percent, etc.

Supplies in my instructions include:

-access to Glowforge or laser cutter

-Arduino Uno and accessories(bread board/wires)

-photoresistors

-Servo motor to be used with Arduino

-Shade cloth any desired percent of sun blockage

-Sand Paper

-Miniature solar panel and solar power regulator for arduino(optional, battery pack works just fine)

Attached is the .svg file I used with a Glowforge laser cutter. You only need 1 set of the curved armature pieces and 4 of the rectangular pieces. You will need to print multiples of the circular/disc pieces of both sizes as you have options to use them in different ways depending on how you decide to put together the structure. You will also need to find a base to fix everything to, try to find a sturdy board that is roughly 10"x10" or greater. Having stands for this board is recommended as well so you may hide the electronic computers underneath the raised base.

Unfortunately all of the images had to be uploaded at the top of the section so you will have to refer back to them as you go. I will explain some of the ways I put together the pieces but it is very flexible as you can laser cut more or less rings/discs to make it work.

Servo motor side-

The cut out in the rectangle piece should fit the standard micro servo motors fairly snug, I used 2 and sandwhiched the smaller inner rectangle cutouts so they stuck out like wings to mount the cables for the photoresistors. the 3 arching pieces I glued carefully to one of the smaller sized rings, making sure the 2 outer arch pieces are spaced and angled equally away from the middle one (for symmetry). I glued the piece that connects to the servo motor onto this smaller ring. For some added stability, I used a larger ring and larger half ring. The half ring was glued to the outer edge of the small ring, and the larger ring was glued to this large half ring so it would be in contact with the 3 arching pieces, giving them another point of connection. Just maker sure however you decide to make this side, leave the Servo arm exposed so it can be screwed in and out of the servo motor itself.

Rotating side-

This side I tried to make a freely spinning/rotating arm almost like a bearing. I glued 3 small discs together, sanding them down and making sure they are as flush with each other as possible to not have any resistance as the arm rotates. For the 3 arches, I sandwhiched them between 2 small rings, making sure they did not stick into the opening of the small ring as this is where the 3 glued discs will go, do not glue the rings and discs together as this is where the arm will spin freely. I then made a stand to hold up the 3 glued discs. The important part with this step is to make sure the discs are level with the servo motor's arm, this will guarantee everything spins smoothly.

Cloth-

for the cloth I just roughly traced the outline of the full arm onto the cloth, leaving about an inch of overhang around the entirety of it. I folded this overhang to the underside of the arm and secured it with hot glue, trying to keep it as taught as possible.

The code is relatively simple for this project and does some basic actions. The basic function is to detect a value of light, consistent with direct sunlight, in 2 different photoresistors. The servo motor is set up to move in the direction of the photoresistor that detects the brighter value of sunlight. This will continue to loop until the shade arm itself blocks the light from hitting the photoresistor, stopping the arm from moving until the sun moves and is able to shine on the photoresistor again. The purpose of the second photoresistor is for different sun angles or with the two photoresistors ideally facing East-West, the one facing east will "reset" the arm when the sun rises and the one facing west will be responsible for moving the arm throughout the way as the sun travels from east to west.

For building the circuit I used an arduino uno and a small breadboard which are both stashed under the base of the structure, so using long enough cables is important. The pin attachments in this photo correspond to the ones in the code provided, but that can always be changed based on preference or if extra peripherals are used with this base project and the pins must be moved to accommodate them, just be sure to change it in the code.

I chose to drill a hole in the base of the board to run the wires from the servo and photoresistors to the Arduino. If you do this just make sure you use long enough cables to reach the servo. for the photoresistors I used Female-male cables into the breadboard, with the female side mounted on the sides of the servo.